ASTM E96 Water Vapor Transmission

 Introduction of ASTM E96 Test

One of the most well-known standards measuring WVTR of materials, especially for barriers and coatings, is ASTM E96. The method measures how much water vapor passes through a material under temperature and humidity conditions. It is essential in industries such as packaging and aerospace, where this level of moisture control has a significant impact on performance and durability. Such results may indicate the materials’ suitability for any specific application under consideration, which requires specifications that demand some degree of resistance to moisture.

What is ASTM E96 Water Vapor Transmission?

ASTM E96 Water Vapor Transmission test is an important test to determine in the case of packaging materials under consideration. This test measures water vapor transfer via semi-permeable and porous samples. The ASTM E96 test measures the rate at which water vapor passes through a material over time, and the measurement is expressed in “perms”; this process is called ASTM E96 perm rating. ASTM E96 permeability refers to measuring how easily water vapor can pass through a material. This property is quantified as the water vapor transmission rate (WVTR), typically expressed in units like grams per square meter per day (g/m²/day).

Scope of ASTM E96 Water Vapor Transmission 

ASTM E96 test determines water vapor transmission (WVT) through materials such as paper, fiberboards, gypsum, plastic films, sheet materials, plaster products, wood products, and plastics. Industry designers and manufacturers might consider this data for packaging material applications. The Desiccant and Water Method are the two methods for measuring permeance. The service conditions have two variations, with one side wetted (low humidity on one side) and high humidity on the other. ASTM E96 test is used to measure water vapor transfer via semi-permeable and porous samples. 

Working Principle of ASTM E96 Water Vapor Transmission

The principle of ASTM E96 mainly concerns measuring water vapor passage rate through a material. In the test, a specimen material is sealed over a cup containing either water or desiccant, depending on whether the test is assessing “wet” or “dry” conditions. The cup shall then be placed in a controlled environment with specified temperature and relative humidity. Over time, the cup weight change indicates the amount of water vapor permeating the material. In calculating the WVTR value, this weight change rate measures the material’s permeability to moisture.

ASTM E96 Test Procedure

For the ASTM E96 test, a cup is filled with distilled water. It is filled so that air space between the sample and the water leaves a small gap of (0.75 inches to 0.25 inches). Then, the cup is wrapped to avoid vapor loss from anywhere but the test sample. The initial weight of this whole assembly is taken and regularly weighed until the results become linear. It must be carefully assured that all weight loss is caused by water vapor transmission through the sample.

ASTM E96 Sample Analysis and Data

Applications of ASTM E96 Water Vapor Transmission

• Automotive and Aerospace 

This standard applies to applications where maintaining moisture resistance of materials within critically important limits is essential. Moreover, it ensures the safety and comfort of people inside vehicles, aircraft, and spacecraft.

• Construction and Building Materials

These evaluations assess materials used in moisture barriers, insulation, roofing, and wall assemblies. Moreover, this approach ensures that such materials effectively prevent moisture accumulation, which could lead to mold, mildew, and structural damage.

• Packaging

It determines the moisture resistance of packing materials for the food, and electronic industries. Furthermore, it assures that products will remain dry, even in packed conditions, preventing spoilage or moisture-related degeneration during storage and shipment.

• Textiles and Fabrics

This standard tests textiles’ breathability for garments, especially outdoor and performance apparel, to ensure they resist outside moisture while allowing perspiration to pass, thus providing comfort.

ASTM E96 Test Conclusion

The ASTM E96  test method is specifically important for the water transmission test of packaging materials, which suggests improvements in their production. The results aid in enhancing their quality, keeping in view the global standards. Also, learn about other tests like the ASTM F1249 Water Vapor Transmission Rate Test.

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